Load cells of this type are used, for example, in weighing scales such as platform scales and especially in bridge scales for weighing vehicles. A plurality of such rocker pin load cells are arranged between the weigh bridge or platform on the one hand and a foundation on the other hand. The weigh bridge or platform is horizontally movable within permissible limits so that the rocker pins of these load cells perform rocking movements to accommodate these horizontal movements of the weigh bridge or platform. Under normal operating conditions these rocking movements do not exceed an angular range of about 10.degree. relative to the vertical. Due to these rocking movements the load cells are exposed not only to vertical forces caused by the loads to be weighed, but also to transverse load components. As a result, it is possible that the load cells perform undesirable rotational movements about their longitudinal axis. Such rotational movements may go as far as tearing the cable connection to the load cell.
U.S. Pat. No. 2,901,235 (Bradley) issued on Aug. 25, 1959 discloses a platform supporting structure for weighing scales with a feature for limiting the rotational movement of the rocker pin in the load cells about their longitudinal axis. A plate 37 rigidly secured to the load cell extends in parallel to the longitudinal axis of the load cell and cooperates with a stop screw 39 extending through a slot 40 in the plate 37. The screw is screwed radially into a fixed base 33. The slot 40 provides a permissible play between the plate 37 and the screw 39. In another version of the Bradley disclosure the load cell housing has an extension 61 with four cut-outs 63 that cooperate with ribs 62 secured to a base 59 for limiting the rotational movement. The cut-outs 63 are dimensioned to provide the permissible play between the extension 61 and the ribs 62.
European Patent EP 0,419,784 B1 (Mills et al.) discloses a weighing apparatus with self-erecting rocker pin load cells. One end of the rocker pin has a non-circular configuration sitting in a non-circular hole of a socket 52. Please see FIGS. 4, 5, 6 and 7 of Mills et al. The socket 52 is restrained against rotation by a notch 114 cooperating with a pin 116 mounted in a base 54. In another embodiment of Mills et al. an end 250 of the rocker pin is cylindrical but equipped with two wings 252 and 254 restrained in a base 260, please see FIG. 14. FIGS. 11, 12 and 13 of Mills et al. show further also rather complicated restraining devices. For example, FIG. 13 shows a radially projecting pin 236 reaching outwardly from the housing 232 into a gap between two also radially extending resilient bumper components 238 and 240 of a U-shaped bracket.
The above described prior art leaves room for improvement especially with regard to simplification and a more compact construction of the rotation limiting elements.